After the 1929 Arab riots against the Jews, the British commission Sir John Hope Simpson to look into the underlying causes of the disturbances. He finds that Jewish land purchase/Arab land sales, Jewish immigration, and the failure to establish self-governing institutions contribute to the unrest. Hope Simpson is heavily influenced by the anti-Zionist attitudes of other British officials. The Passfield White Paper, issued the same day, uses Hope Simpson’s findings to suggest restrictions on Jewish land purchases and immigration. These are implemented 10 years later with the May 1939 White Paper.